A PRESENTATION ONFORMWORK

CONTENTS• DEFINITION OF FORMWORK• REQUIREMENTS• FORM MATERIALS AND ACCESSORIES• CONCRETE FORM WORK• TYPES OF FORM WORK• FUNCTION• FORM WORK DESIGN• MATERIAL FOR FORM WORK

CONSTRUCTION

DEFINITION

•Formwork is a type of board which is used to hold wet concrete till it dries. It is a temporary structure made of wood or steel. The Formwork boarding is removed when the concrete dries. It is used for construction of slabs, columns, beams in homes, business complexes, and other buildings.

REQUIREMENTS

– Safe – must hold concrete in place until the concrete gets hardened.

– Economical – provides desired shape and surface texture

Form Materials and Accessories

• CM 420Temporary Structures

• Practically all formwork jobs require some lumber.• Local supplier will advise what material and sizes

are in stock or promptly obtainable, and the designer or builder can proceed accordingly.

• Southern yellow pine and Douglas fir, sometimes called Oregon pine ,plywood are widely used in structural concrete form.

• They are easily worked and are the strongest in the softwood group. Both hold nails well and are durable.

• They are used in sheathing, studs, and wales.

Form Materials and Accessories

Form Materials and Accessories

Form Materials and Accessories

Form Materials and Accessories

Plywood• Plywood at the

bottom face grain parallel to span is used the strong way. With face grain perpendicular to the span direction, the specimen at the top is used the weak way.

Vertical Loads• Vertical loads on formwork include:

– the weight of reinforced concrete– the weight of forms themselves (dead load)– the live loads imposed during the construction process

(material storage, personnel and equipment).– The concrete which weighs 20 to 25 Kn / cu. m

Vertical Loads

Live load including power buggy and the concrete crew

(A minimum live load of 75 psf is recommended for design where power buggies are used)

CONCRETE FORMWORK

• Formwork being erected

• Most of the pads and concrete footing poured

TYPES OF FORMWORK

Temporary Structure - Temporary structure required to safely support concrete until it reaches adequate

strength.Permanent Structure

Forms mold the concrete to desired size and shape and control its position and alignment

Formworks also act as a temporary structure that support:

a) it’s own weight b) The freshly placed concrete c) Construction live loads (material , human, logistic)

FUNCTION

A good formwork would have the followingcharacteristics that is:a)Safeb)Cost effective or economicalc)High Quality – finished concrete surface is of acceptable quality

- in the correct location - able to produce the required shape and surface

FORMWORK DESIGN

Loads include in design process are as followsa) Fresh concreteb) Rebarc) Formwork materiald) Wind and lateral loadse) Live loads due to – Formwork construction - Reinforcing installation

- Concrete placement

MATERIAL FOR FORMWORK CONSTRUCTION

Among the material that can be used for construction of formwork: a) Timberb) Steel c) Glass Reinforced Plastic

TIMBER FORMWORK

Timber Formwork:After Concrete Was

Poured

Timber Formwork : For The Slab

STEEL FORMWORK

• The first floor circular columns were constructed using steel column forms. The steel column form should be oiled

before concreting.

• After concreting to the first floor columns, the steel column forms

were dismantled easily.

Causes of Formwork Failure

• Improper stripping and shore removal• Inadequate bracing• Vibration• Unstable soil under mudsills, shoring not

plumb• Inadequate control of concrete placement• Lack of attention to formwork details

Inadequate bracing

More frequent causes of formwork failureInadequate cross bracing and horizontal

bracing of shores is one of the factors most frequently involved in formwork accidents.

Vibration

Forms sometime collapse when their shores/ jack are displaced by the vibration caused

passing traffic movement of workers & equipment on the formwork the effect of vibrating concrete to consolidate it